1. Field of the Invention
The present invention relates to a receiving device for adjusting the energy of a received signal sent over a transmission line.
2. Description of the Related Art
For transmission of a digital signal over a transmission line, a receiving side is disadvantageously confronted with an overshoot, an undershoot, or any other distortion that might occur because part of the energy of a signal is reflected at the time at which the signal level changes. Various proposals have been made for a technology to suppress a waveform distortion. For example, JP-A-2001-127805 describes a technology in which, assuming that the voltage level of a signal makes a transition between low and high levels, a termination circuit 11 for a transmission line tentatively decreases the impedance at a terminal 5 during a time delay which is given by a delay circuit 20.
JP-A-2000-353945 describes a technology for continuously varying an output impedance on a signal transmitting side when the level of an output signal changes. JP-A-2000-059444 describes a technology in which an attenuation circuit 112 attenuates an overshoot or an undershoot on a receiving side and a charging/discharging circuit 114 charges or discharges the output terminal of the attenuation circuit 112 with respect to a supply voltage or a ground voltage.
In an actual communication network, if numerous communication nodes are connected onto a transmission line, an energy distribution on the transmission line may become uneven, depending on particular aspects of the signal transmission. Unnecessary signal energy is received at some communication nodes, while insufficient energy is received at other communication nodes posing a disadvantage in that reception cannot be carried out normally or uniformly. The foregoing patent documents fail to describe such disadvantages.